1. Field of Invention
The present invention relates to an improved wide throat high-pressure high-rpm rotary union which is greatly simplified in design, yet provides a number of advantages over state-of-the-art rotary unions, such as the ability to channel water under high pressure without pressure drop, the ability to provide external indication of seal failure, the ability to protect bearings from water damage, simplified maintenance, and longer operating life under high-pressure high-rpm conditions. These design features particularly provide for ease of on-site seal replacement and low down time.
2. Discussion of the Related Art
In industrial and residential environments fluid pressure is used for cleaning and washing applications. To effect good cleaning or scouring, it is desirable to impart motion to the spray fluid as by rotation of the spray fluid head. This motion distributes the fluid so as to impact all exposed areas of the work surface, and assists in dislodging and flushing dirt or other unwanted matter.
Rotary unions, often referred to as swivel joints, are used in applications when necessary to couple the stationary outlet of fluid sources (i.e., water main, hoses, etc.) to rotating sprayer devices (e.g., rotating spray nozzles or sprayer arms). These rotary unions are used, for example, in devices for delivering sprays of fluid such as water, often with detergents or additives, onto work surface to be treated, as in driveway or sidewalk cleaning operations or automobile washing operations.
Examples of rotating spray nozzle assemblies presently in use include those disclosed in U.S. Pat. No. 3,950,045. This patent teaches a rotatable bearing assembly comprising a relatively fixed part and a rotatable part designed for high-speed operation at pressures of up to 3,000 psi, and including a governor for limiting the rotational speed of the rotatable part. This patent addresses the problem of extremely high frictional forces that develop between the bearing surfaces, which in turn cause high wear causing a breakdown of the bearing. To avoid this problem and reduce friction, this patent teaches that the bearing surfaces are to be lubricated by permitting a leak-by of, e.g. &lt;10%, of washing fluid (col. 3, line 17). However, this leakage undesirably reduces the pressure flowing to the spray head, reducing washing power.
U.S. Pat. No. 5,104,044 teaches a hydroactuatable spinner comprising a turbine assembly to impart rotation to a spray rotor of pressures of 500-1000 p.s.i. The turbine uses impelling fluid pressure causing some loss of flow. Conventional O-rings are used in a basic design to prevent the leakage within the unit, but these O-rings are liable to rapid wear and there is no built-in indicator to show when the O-rings are worn. Further, the pressure to which this design can be subjected is limited.
U.S. Pat. No. 5,269,345 teaches a device for transferring a pressure medium from a stationary first component into a second component, which is rotatably driven within the first component. Between the two components an annular chamber is provided, to which are connected an inlet line and an outlet line for guiding the medium to the consuming device. Radially extending sealing slots are defined between a first stationary component and a second component that is inserted into the first stationary component such that it is rotatably driveable therein. These two sealing slots are simultaneously movable and have adjustable slot widths. There is no easy of determining if the sealing surfaces are worn and need replacing. Furthermore, the assembly is not simple and is not designed to be repaired in the field.
U.S. Pat. No. 5,456,412 teaches a rotary spray nozzle on wheels. The rotary spray arm is caused to rotate and to achieve rotational cleaning in a rotational direction opposite from the water jet impingement angle. A pressure ring, preferably in the form of a V-ring with coil spring inserts, is positioned between the housing and rotary axle. A thrust bearing is also provided to retain the rotary axle in place. This seal and bearing arrangement cannot be subjected to very high pressures, is liable to wear, and there is no easy way to tell when the seal and bearing require replacement.
U.S. Pat. No. 5,501,396 teaches a method of sealing water flowing through a central bore of a rotary union. The seal is formed by a pair of hard sealing surfaces pressed together by a spring and surrounded by an O-ring. This compressing causes drag which reduces the efficiency of the pressure wash system. Further, the central bore passage is characterized by many changes in diameter, which creates turbulence in the flow of water and results in a pressure drop in the high-pressure water flowing through between the annular bore inlet and outlet. Further, there is no easy way of determining if the seals are worn, and when it is time to replace the seals. The assembly is not designed to be easily rebuilt on-site, and has to be returned to the manufacturer for any repairs or overhaul.
U.S. Pat. No. 5,456,413 teaches a rotary water blast nozzle that includes an inner body member and a mandrel that supports a spray head having an internal bushing that rotates on the mandrel. The combination of the operating pressures acting inward on the outside of the bushing between seals, and the gradually diminishing pressures acting outwardly in the clearance from the center toward the ends of the bushing, together with the frusto-conically shaped sections of the bushing, cause a uniform inward deflection that reduces the clearance in proportion to the operating pressure to inhibit leakby. This bearingless system is not designed for high-pressure use, the seals wear gradually, and there is no way to tell when the seals are in need of replacement.
U.S. Pat. No. 4,296,952 teaches a simple rotary joint that utilizes a single anti-friction bearing with a self-aligning or floating seal. Vent holes are provided in the housing sidewall adjacent the seal assembly for venting of any fluid leakage in the case of seal wear, but the bearings are not protected from this leakage and seal leakage requires immediate attention. The seal is formed from materials such as carbon graphite or ceramic. Although such materials provide a good seal, the seal faces have a relatively short useable lifetime. Furthermore, replacement of a damaged or scored rotating seal member requires replacement of the entire rotor assembly.
U.S. Pat. No. 4,817,995 teaches a rotary union that includes a seal assembly having rotating and non-rotating seal members and a compression spring maintaining them in sealing engagement. This spring pressure governs the unit's ability to handle high pressure, since pressure in excess of the spring pressure could overcomes the spring compressive force, causing a space and thus a leak between the sealing surfaces. There are also three vent holes that are located in the housing sidewall by the seal assembly. These vent holes enable fluid to be conducted to the outside of the housing when the seals are worn. However, if the seals are not replaced there is no means to keep the leaking fluid out of the ball bearings. Another problem with this system is that it does not provide a smooth channel for the flow of fluid. The fluid enters through a perpendicular inlet port then encounters obstructions such as spring and recesses. Inefficient water conductance results in a drop in fluid pressure and thus reduced cleaning effectiveness.
High-pressure fluid such as water has been employed for scour cleaning, and at the same time it is relied upon to drive rotating spray heads. In such devices it is equally important that the water and its power be conserved while still effecting the cleaning task.
Thus it would be desirable to have a rotary union that is simple and readily rebuildable so that even relatively unskilled attending personnel may be able to maintain and replace worn parts with the minimum use of tools. This would help in reducing costs and down time for the apparatus on which the rotary union is used.
An objective of the present invention is to provide a new and improved wide throat rotary union designed for high-pressure, high through-put (i.e., high gpm), high rpm liquid blast cleaning operations, which rotary union is constructed and arranged to obviate the foregoing problems.
Another objective of the present invention is to provide a rotary union of the type described which incorporates means to indicate wear of seals.
Still another objective of the present invention is to provide a new and improved rotary union of the type described which is simpler in construction, more efficient in operation, more economical to maintain and operate than prior devices.